Thermionic and field emission devices are well known and are used in a variety of applications. Generally, thermionic electron emission devices operate by ejecting hot electrons over a potential barrier and field emission devices operate by causing electrons to tunnel through the barrier. Examples of specific devices include those disclosed in U.S. Pat. Nos. 6,229,083; 6,204,595; 6,103,298; 6,064,137; 6,055,815; 6,039,471; 5,994,638; 5,984,752; 5,981,071; 5,874,039; 5,777,427; 5,722,242; 5,713,775; 5,712,488; 5,675,972; and 5,562,781 each of which is incorporated herein by reference.
Although basically successful in many applications (i.e. used in cathode ray tubes, and other vacuum devices), thermionic devices have been less successful than field emission devices, as field emission devices generally achieve a higher current output under an electrical field of the same intensity. Despite this advantage, most field emission devices suffer from a variety of disadvantages that limit their potential uses, including materials limitations, versatility limitations, cost effectiveness, lifespan limitations, and efficiency limitations, among others.
Electrodes are widely used in electronic devices and power sources. Some common applications for electrodes are in fluorescent light bulbs, electrochemical cells, and similar devices. However, in many applications these electrodes become corroded or in some cases covered in deposits which dramatically reduce their performance, reliability, and useful life. For example, fluorescent lights generally have low luminescence as compared to filament type light sources. Typical electrodes are operated at high temperatures and are made of materials which are conducive to either chemical reaction and/or mechanical attraction to common compounds used in conjunction with electrodes. Various efforts have been made to improve reliability and performance of electrodes through the use of specific materials and/or coatings. For example, electrodes are sometimes coated with a conductive material to improve the lifespan of the electrode. Such coatings are performed by brazing, deposition, and similar techniques. However, such coatings only marginally improve performance and lifespan. Some metallic coatings have proven more effective at improving electrode lifespan, however suffer from increased costs of manufacture.
As such, devices that provide a high voltage output, have extended life, and operate at low temperatures continue to be sought through ongoing research and development efforts.